1. Line a 10 inches (26cm) springform tin with baking parchment and grease lightly. Set aside. Wash and dry the damson plums, half them and remove the stones. Set aside.

 

2. Add the flour for the base together with the sugar and baking powder to a large bowl and mix until well combined. Add the cold butter in small pieces, mix with the flour and cut into pea-sized pieces with a pastry blender or knife. Add the egg and mix/knead quickly until you get a smooth dough. Roll out the dough on a floured surface slightly larger than the tin. Place in the prepared tin and press to the bottom and sides to form a nice crust (almost up to the edge). Place in the fridge for about 30 minutes to cool down and firm up.

 

3. Preheat the oven to 350°F (180°C). Add the butter and sugar for the filling to a large bowl and mix until light and fluffy. Add the vanilla extract and the egg yolks and mix until well combined. Mix the semolina with the cornstarch and add together with the curd (Quark) and mascarpone to the bowl and mix well. Whisk the egg whites in a separate bowl until stiff peaks form, add to the mixing bowl and gently fold in. Pour the batter on the prepared crust and smooth out the top. Place the halved plums all over the top (sprinkle with some cinnamon/sugar if you like) and bake for 55-60 minutes or until the cake is set and is moving only a little in the center when you shake the baking tin. Take out of the oven and let cool down completely. After that place in the fridge for at least 2 hours before cutting. Serve with some whipped cream if you like that.